certification — a document attesting the truth of a fact or statement
declaration — A declaration is an official announcement or statement.
oath — a solemn appeal to a deity, or to some revered person or thing, to witness one's determination to speak the truth, to keep a promise, etc.: to testify upon oath.
okay — to put one's endorsement on or indicate one's approval of (a request, piece of copy, bank check, etc.); authorize; initial: Would you OK my application?
pronouncement — a formal or authoritative statement.
ratification — the act of ratifying; confirmation; sanction.
testimonial — a written declaration certifying to a person's character, conduct, or qualifications, or to the value, excellence, etc., of a thing; a letter or written statement of recommendation.
testimony — Law. the statement or declaration of a witness under oath or affirmation, usually in court.
affirmation — the act of affirming or the state of being affirmed
allegation — An allegation is a statement saying that someone has done something wrong.
protestation — the act of protesting or affirming.